Bring a large pot of water to a boil. Add potato; simmer until tender, about 20 minutes. Drain. Return to the pot and pour in chicken stock. Add spinach and pea shoots.

Heat oil in a large skillet. Add asparagus, onion, celery, mint, and sage. Cook and stir until asparagus is tender, 5 to 10 minutes.

Stir asparagus mixture into the chicken stock in the pot. Simmer soup over medium-low heat until flavors combine, about 30 minutes. Remove from heat.

Pour soup into a food processor; process until smooth, about 20 seconds. Pour back into the pot. Stir in creme fraiche. Season with salt and pepper.